The publications and other materials used herein to illuminate the background of the invention, and in particular, cases to provide additional details respecting the practice, are incorporated by reference.
Hydroxymatairesinol (HMR) which has the formula
is a lignan, i.e. a class of phenolic substances widely distributed in plants. Hydroxymatairesinol appears as two diastereomers, namely (−) hydroxymatairesinol (also denoted HMR 2 isomer) and (−) allo-hydroxymatairesinol (HMR 1 isomer).
Hydroxymatairesinol has been disclosed to possess valuable therapeutical properties and has been suggested for use in prevention of cancer, certain hormone-dependent diseases and/or cardiovascular diseases, or for increasing the enterolactone level in a person's serum. Hydroxymatairesinol has thus been suggested for use as a food supplement or as a medicament (International patent publication WO 00/59946). It has further been found that the HMR 2 isomer is more biologically active than the HMR 1 isomer.
Considerable amounts of lignans are found in coniferous trees. The type of lignans differs in different species and the amounts of lignans vary in different parts of the trees. The typical lignans in heart wood of spruce (Picea abies) are hydroxymatairesinol (HMR), α-conidendrin, conidendric acid, matairesinol, isolariciresinol, secoisolariciresinol, liovil, picearesinol, lariciresinol and pinoresinol (Ekman 1979). The far most abundant single component of lignans in spruce is hydroxymatairesinol (HMR), about 60 percent of total lignans, which occurs mainly in unconjugated free form. Lignan concentration in thick roots is 2–3 percent. Abundance of lignans occur in the heart wood of branches (5–10 percent) and twists and especially in the knots, where the amount of lignans may be higher than 10 percent (Ekman, 1976 and 1979). These concentrations are about hundred-fold compared to ground flax powder known as lignan-rich material.
It has been suggested to isolate hydroxymatairesinol from compression-wood fiber. These fibers originate from compression wood of stems and knots (oversize chip fraction) and they are known to weaken the quality of paper (Ekman, 1976).
Earlier described methods for the recovery of hydroxymatairesinol from wood:    Ekman 1976 and Ekman 1979 describe a laboratory extraction method for recovering hydroxymatairesinol from ground heartwood of Norway spruce. The wood material was first Soxhlet-extracted with hexane to remove lipophilic components. Then the wood material was re-extracted with a mixture of acetone and water (9:1) to give a mixture of crude lignans. Hydroxymatairesinol was isolated from the mixture by chromatography.    Freudenberg & Knof, 1957, described the extraction of wood meal with acetone and water. The extract was separated into different fractions by formamide, water and ether. The hydroxymatairesinol-rich fraction was separated into the two isomers (amorphous (−) hydroxymatairesinol and crystalline (−) allo-hydroxymatairesinol) either by chloroform and water, or by crystallizing the isomer (−) hydroxymatairesinol potassium acetate adduct by adding alcohol and potassium acetate to the hydroxymatairesinol-rich fraction containing both isomers.
However, no suitable process for large scale recovery of HMR from wood has been described in the literature.
The present invention fulfils a great need for a convenient production method of hydroxymatairesinol in large scale from wood material. The new method has many advantages over previously described methods:    the method comprises only a few steps, in principle only the extraction step and the precipitation (e.g. crystallization) step of the hydroxymatairesinol complex formed    the same kind of solvent can be used in both steps    solvents accepted by the health authority regulations can be used in both steps    there is no need to separate the extract into different fractions before the addition of the complexing agent    the complex formed can be used as such as a commercial product    the product derived has a purity which is good enough for end use of the product.